Positioning jig device for vehicle body frame

ABSTRACT

In a welding station, one end of a positioning jig is held by a positioning robot, and the other end of the positioning jig is held by a positioning jig holder mechanism. The positioning robot is moved for positioning and fixing a vehicle body frame, which is fixed to the positioning jig, in any attitude, and a desired welding operation is performed on the vehicle body frame.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention claims priority under 35 USC 119(a)-(d) and 365(b)based on Japanese patent application No. 2003-082134, filed on Mar. 25,2003. The subject matter of this priority document is incorporated byreference herein.

TECHNICAL FIELD

The present invention relates to a positioning jig device for supplyinga vehicle body frame to a predetermined working position and positioningand fixing the vehicle body frame.

BACKGROUND ART

Heretofore, a welding system for welding vehicle body frames, forexample, has a plurality of welding stations with welding robots.Vehicle body frames are positioned on jigs, and are supplied from aworkpiece feed path to the respective welding stations where the vehiclebody frames are welded.

Jigs for positioning the vehicle body frames in the welding stations arerequired for each of the various respective vehicle body frames. Thepositioning relationship between the vehicle body frames supplied to thewelding stations and the welding robot differs depending on thecombinations of the types of the vehicle body frames and the types ofthe jigs and welding robots corresponding to the vehicle body frames.Therefore, it is necessary to provide as many dedicated jigs as thenumber of the combinations. As the number of types of vehicle bodyframes and the number of types of welding robots increase, more types ofjigs are required, resulting in an increase in the cost of thefacilities. Furthermore, since the positional relationship between eachjig and each welding robot needs to be adjusted once in every two orthree months, the management process for maintaining positional accuracyis complicated and troublesome.

According to a conventional arrangement disclosed in Japanese Patent No.3351753, for example, each welding station has a positionally adjustablepositioner positioning a vehicle body frame, and a vehicle body frame issupplied from a workpiece feed path to each positioner by a feed robot.The vehicle body frame is adjusted to a position and attitude dependingon the welding robot and then welded by the welding robot. Thepositioners disposed in the respective welding stations can be commonlydesigned for use with the welding robots in the respective weldingstations.

However, it is essential for each welding station to have its ownpositioner, and at least positioners of different structures dependingon the types of vehicle body frames are required.

SUMMARY

It is an object of the present invention to provide a positioning jigdevice which is capable of highly accurately positioning a vehicle bodyframe using a minimum number of required positioning jigs depending uponthe types of vehicle body frames only.

It is another object of the present invention to provide a positioningjig device for a vehicle body frame, which is capable of reducing thecost entailed by positioning jigs.

According to the present invention, a vehicle body frame fixed to apositioning jig which is constructed depending on the form of thevehicle body frame is supplied to a working position by a positioningrobot. Then, an engaging member of a positioning jig holder mechanismengages an end of the positioning jig, and the positioning robotpositions the vehicle body frame in a desired working attitude. At thistime, since the positioning jig is supported by the positioning robotand the positioning jig holder mechanism, the vehicle body frame canstably be worked upon as desired with high accuracy.

The engaging member may be swingably supported and may be supported fordisplacement toward the positioning jig, so that the positioning jig canbe set to a desired working attitude by the positioning robot.

The engaging member may be displaceable through a resilient member toabsorb shocks that are produced when the positioning jig and theengaging member engage each other.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a welding system;

FIG. 2 is a side elevational view of the welding system of FIG. 1showing the manner in which a vehicle body frame is positioned by apositioning robot and a positioning jig holder mechanism in a weldingstation;

FIG. 3 is a perspective view of the welding system of FIG. 1 showing themanner in which the vehicle body frame is positioned by the positioningrobot and the positioning jig holder mechanism in the welding station;

FIG. 4 is a cross-sectional view of the welding system of FIG. 1 takenalong line IV-IV of FIG. 1; and

FIG. 5 is a cross-sectional view of the welding system of FIG. 1, partlyomitted from illustration, taken along line V-V of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a plan view of a welding system 10 incorporating a positioningjig device for a vehicle body frame according to the present invention.

The welding system 10 is a system for welding vehicle body frames 12that are supplied in a temporarily assembled state. The welding system10 includes a vehicle body frame placement unit 16 having a placementtable 14 for placing a plurality of vehicle body frames 12 thereon, awelding station 18 for welding a vehicle body frame 12 supplied from thevehicle body frame placement unit 16, and a positioning robot 22 havinga positioning jig 20 for feeding a vehicle body frame 12 from thevehicle body frame placement unit 16 to the welding station 18 andpositioning the vehicle body frame 12 in the welding station 18.

The welding station 18 has a positioning jig holder mechanism 24 forholding the positioning jig 20 in cooperation with the positioning robot22, and two welding robots 26, 28 for welding the vehicle body frame 12.

As shown in FIG. 2, the positioning robot 22 has a first arm 32 mountedon a base 30 and rotatable in the direction indicated by the arrow A, asecond arm 34 mounted on an end of the first arm 32 and rotatable in thedirection indicated by the arrow B, a third arm 36 mounted on an end ofthe second arm 34 and rotatable in the direction indicated by the arrowC, a fourth arm 38 mounted on an end of the third arm 36 and rotatablein the direction indicated by the arrow D, and a fifth arm 40 mounted onan end of the fourth arm 38 and rotatable in the direction indicated bythe arrow E. The positioning jig 20 is coupled to an end of the fiftharm 40.

As shown in FIG. 3, the positioning jig 20 comprises a substantiallyL-shaped jig base 42 having an end coupled to the fifth arm 40 of thepositioning robot 22, a substantially L-shaped joint arm 48 mounted onthe other end of the jig base 42 by joint plates 44, 46, first securingunits 50, 52 disposed on the jig base 42, and second securing units 54,56 disposed on the upper joint plate 44.

The vehicle body frames 12 are provided for use in four-wheel buggies,for example. Each of the vehicle body frames 12 has two upper frames 58,60, two lower frames 62, 64, and a plurality of auxiliary frames 66interconnecting the frames 58, 60, 62, 64. Brackets 72, 74 havingrespective holes 68, 70 for supporting respective suspensions aredisposed on respective front portions of the lower frames 62, 64.Brackets 80, 82 having respective holes 76, 78 for pivotally supportingrespective ends of swing arms are disposed on respective rear portionsof the lower frames 62, 64.

The first securing units 50, 52 of the positioning jig 20 haverespective brackets 86, 88 erected on the jig base 42, and respectivethreaded members 94, 96 disposed on respective upper portions of thebrackets 86, 88, with fastening bolts 90, 92 threaded through therespective threaded members 94, 96. As shown in FIG. 4, the secondsecuring units 54, 56 have respective brackets 98, 100 erected onrespective opposite ends of a support plate 84 which is fixedly mountedon the joint plates 44, 46, and respective threaded members 106, 108disposed on respective upper portions of the brackets 98, 100, withfastening bolts 102, 104 threaded through the respective threadedmembers 106, 108. Stiffener ribs 110, 112 are disposed on the respectivebrackets 98, 100.

An engaging member 114 is disposed on an end of the joint arm 48 of thepositioning jig 20. As shown in FIG. 5, the engaging member 114 has anopening 116 and a recess 118 having an inner space that is wide relativeto the recess 118.

The positioning jig holder mechanism 24 has two support posts 122, 124erected on a base 120, bearings 126, 128 disposed on respective upperends of the support posts 122, 124, and a support 134 rotatablysupported by rotational shafts 130, 132 which are pivotally supported bythe bearings 126, 128.

Upper portions of the support posts 122, 124 are interconnected by ajoint plate 136. A substantially L-shaped fixed arm 138 has an end fixedto the support posts 122, 124, and has a hole 142 defined in an upperend thereof. A securing pin 140 for securing the support 134 is insertedthrough the hole 142.

The rotational shafts 130, 132 are disposed on respective opposite sidesof a central portion of the support 134. Brackets 144, 146 between whichthe upper end of the fixed arm 138 extends are disposed on an end of thesupport 134. The brackets 144, 146 have respective holes 148, 150defined therein, with the securing pin 140 inserted therethrough.

The support 134 has an oblong hole 152 defined in the other end thereof,and a hollow cylindrical support sleeve 154 is inserted into the oblonghole 152 from the other end of the support 134. Metal seals 156, 158 aredisposed on the inner circumferential surface of the support sleeve 154,and a cylindrical rod 160 is inserted through the metal seals 156, 158for displacement and rotation with respect to the support sleeve 154.

The rod 160 has a flange 162 on an end thereof for engaging the supportsleeve 154 to prevent the rod 160 from being removed from the supportsleeve 154. The rod 160 has a hole 164 defined in the end thereof andhouses therein a helical spring 166 (resilient member) for normallybiasing the rod 160 to move in a direction so as to project outwardlyfrom the support 134. The support 134 has a vent hole 168 communicatingwith the oblong hole 152 and vented to the outer space. Air can flowthrough the vent hole 168 into and out of the oblong hole 152 forallowing the rod 160 to be easily displaced with respect to the oblonghole 152.

A cylinder 170 is disposed on the other end of the rod 160. The cylinder170 is capable of rotational movement so as to drive two confrontingsets of engaging members 172, 174, 176, 178 toward and away from eachother in a direction substantially orthogonal to a longitudinal axis ofthe rod 160. The engaging members 172, 174, 176, 178 have respectiveteeth 180 for engaging in the recess 118 defined in the engaging member114 that is disposed on the joint arm 48 of the positioning jig 20.

The welding system 10 according to the present embodiment is basicallyconstructed as described above. Operation of the welding system 10 willbe described below.

First, the positioning jig 20 corresponding to the type of the vehiclebody frame 12 is mounted on the fifth arm 40 of the positioning robot22. Then, the positioning robot 22 is actuated to move the positioningjig 20 to the vehicle body frame placement unit 16. Thereafter, avehicle body frame 12 which has been assembled by temporary welding issecured to the positioning jig 20.

For securing the vehicle body frame 12 to the positioning jig 20, asshown in FIG. 3, the fastening bolts 90, 92 are threaded respectivelyinto the threaded members 94, 96 of the first securing units 50, 52until the tip ends of the fastening bolts 90, 92 are insertedrespectively into the holes 68, 70 defined in the brackets 72, 74 on thelower frames 62, 64 of the vehicle body frame 12. Similarly, as shown inFIG. 4, the fastening bolts 102, 104 are threaded respectively into thethreaded members 106, 108 of the second securing units 54, 56 until thetip ends of the fastening bolts 102, 104 are inserted respectively intothe holes 76, 78 defined in the brackets 80, 82 on the lower frames 62,64 of the vehicle body frame 12.

The brackets 72, 74 are components for mounting suspensions on thevehicle body frame 12, and the brackets 80, 82 are components formounting swing arms on the vehicle body frame 12. The vehicle body frame12 is highly accurately positioned on and fixed to the positioning jig20, using these brackets.

The vehicle body frame 12 may be automatically secured to thepositioning jig 20 by placing the vehicle body frame 12 on thepositioning jig 20 that has been moved to the vehicle body frameplacement unit 16 by the positioning robot 22, using a placement robot,and threading the fastening bolts 90, 92, 102, 104 using a nut runner orthe like that is actuated by a servomotor.

After the vehicle body frame 12 has been secured to the positioning jig20, the positioning robot 22 is actuated again to feed the vehicle bodyframe 12 together with the positioning jig 20 to the welding station 18.At this time, as shown in FIG. 5, the securing pin 140 is inserted intothe holes 148, 150 in the end of the support 134 through the hole 142 inthe fixed arm 138 to keep the support 134 of the positioning jig holdermechanism 24 horizontal in the welding station 18. The cylinder 170 ofthe positioning jig holder mechanism 24 is actuated to bring theengaging members 172, 174, 176, 178 toward each other.

The positioning robot 22 is actuated to displace the engaging member 114disposed on the end of the joint arm 48 of the positioning jig 20 in thedirection indicated by the arrow F in FIG. 5 until the teeth 180 of theengaging members 172, 174, 176, 178 of the positioning jig holdermechanism 24 are inserted into the recess 118 in the engaging member114. At this time, since the rod 160 which supports the engaging members172, 174, 176, 178 is displaceable in the directions indicated by thearrow H by the helical spring 166 disposed in the oblong hole 152 in thesupport 134, shocks produced when the engaging member 114 and theengaging members 172, 174, 176, 178 engage each other are absorbed.

Then, the cylinder 170 is actuated to separate the engaging members 172,174, 176, 178 by moving them away from each other, whereupon the teeth180 engage the engaging member 114 to join the end of the positioningjig 20 to the support 134. As a result, the positioning jig 20 to whichthe vehicle body frame 12 is fixed has one end held by the positioningrobot 22 and the other end by the positioning jig holder mechanism 24.Thereafter, the securing pin 140 is removed from the brackets 144, 146of the support 134, allowing the support 134 to swing about therotational shafts 130, 132 in the directions indicated by the arrow G.

Then, the positioning robot 22 moves the first arm 32, the second arm34, the third arm 36, the fourth arm 38, and the fifth arm 40 to set thevehicle body frame 12 to a desired attitude in the welding station 18.At this time, because the rod 160 of the positioning jig holdermechanism 24 moves in the directions indicated by the arrow G, or turnsabout the support sleeve 154, or is displaced with respect to thesupport sleeve 154 as the positioning robot 22 moves, the positioningrobot 22 can easily set the vehicle body frame 12 to a desired attitude.

After the vehicle body frame 12 has been positioned in a desiredattitude, the welding robots 26, 28 disposed on opposite sides of thevehicle body frame 12 are actuated to weld the vehicle body frame 12. Atthis time, inasmuch as the vehicle body frame 12 is positioned and heldby the positioning robot 22 and the positioning jig holder mechanism 24,the vehicle body frame 12 does not swing while being welded, but remainshighly accurately positioned in the welding process. For betteroperation efficiency, the attitude of the vehicle body frame 12 may bechanged, and the welding process may be continued.

The positioning jig device for a vehicle body frame according to thepresent invention is also applicable to the positioning of vehicleframes other than those of four-wheel buggies, e.g., vehicle frames ofthree- and two-wheel vehicles.

According to the present invention, since the positioning jig is held bythe positioning robot, and a vehicle body frame is supplied to andpositioned in a working position, it is not necessary to providededicated jigs in respective working positions, and the cost entailed byjigs on a working line is greatly reduced.

Different vehicle body frames can easily be coped with by replacing thepositioning jig held by the positioning robot.

The positioning attitude of the vehicle body frame in each workingposition can desirably be set by the positional control of thepositioning robot depending on the type of the vehicle body frame.

Furthermore, since the positioning jig has its opposite ends heldrespectively by the positioning robot and the positioning jig holdermechanism, the vehicle body frame is positioned highly stably so as tobe worked upon highly accurately.

The positioning jig device for a vehicle body frame according to thepresent invention is applicable to various vehicle bodies insofar asthey have a frame structure.

1. A positioning jig device for a vehicle body frame, comprising: apositioning jig for positioning and fixing the vehicle body frame inspace; a positioning robot for holding a first end of said positioningjig, supplying said positioning jig to a working position for saidvehicle body frame, and positioning said vehicle body frame in a desiredattitude; and a positioning jig holder mechanism for movably holdingsaid positioning jig, said positioning jig holder mechanism beingdisposed in said working position and having an engaging member which isdetachably engageable with a second end of said positioning jig.
 2. Thepositioning jig device according to claim 1, wherein said positioningjig comprises a securing unit for positioning and fixing said vehiclebody frame relative to said positioning jig.
 3. The positioning jigdevice according to claim 1, wherein said positioning jig comprises arecess engageable by said engaging member of said positioning jig holdermechanism.
 4. The positioning jig device according to claim 1, whereinsaid positioning robot comprises a multi-axis robot for setting saidvehicle frame to the desired attitude while the second end of saidpositioning jig is engaging said engaging member of said positioning jigholder mechanism.
 5. The positioning jig device according to claim 1,wherein said positioning jig holder mechanism has a support by whichsaid engaging member is swingably supported and which supports saidengaging member for displacement toward the second end of saidpositioning jig.
 6. The positioning jig device according to claim 5,wherein said support supports said engaging member for rotation about anaxis along which said engaging member is displaceable.
 7. Thepositioning jig device according to claim 5, wherein said support has anattitude securing member for securing the attitude of the support withrespect to the second end of said positioning jig.
 8. The positioningjig device according to claim 5, wherein said engaging member issupported by said support for displacement toward the second end of saidpositioning jig through a resilient member.
 9. The positioning jigdevice according to claim 5, wherein said engaging member is actuatableby an actuating mechanism for engagement with the second end of saidpositioning jig.
 10. The positioning jig device according to claim 1,including a welding robot disposed in said working position for weldingsaid vehicle body frame which is positioned and fixed by saidpositioning jig.
 11. A positioning jig device for a vehicle body frame,comprising: a positioning jig for positioning and fixing the vehiclebody frame in space; a positioning robot for holding a first end of saidpositioning jig, supplying said positioning jig to a working positionfor said vehicle body frame, and positioning said vehicle body frame ina desired attitude; and a positioning jig holder mechanism for movablyholding said positioning jig, said positioning jig holder mechanismbeing disposed in said working position and is operably connected to asecond end of said positioning jig.
 12. The positioning jig deviceaccording to claim 11, wherein said positioning jig holder mechanismcomprises an engaging member which is detachably engageable with thesecond end of said positioning jig, and wherein said said second end ofsaid positioning jig comprises a recess engageable by said engagingmember of said positioning jig holder mechanism.
 13. The positioning jigdevice according to claim 12, wherein said engaging member comprises twoconfronting sets of engaging arms, said engaging arms configured to movein a direction which is one of toward each other and away from eachother upon actuation of the engaging member.
 14. The positioning jigdevice according to claim 12, wherein said positioning jig holdermechanism has a support by which said engaging member is swingablysupported and which supports said engaging member for displacementtoward the second end of said positioning jig.
 15. The positioning jigdevice according to claim 14, wherein said support has an attitudesecuring member for securing the attitude of the support with respect tothe second end of said positioning jig.
 16. The positioning jig deviceaccording to claim 14, wherein said engaging member is supported by saidsupport for displacement toward the second end of said positioning jigthrough a resilient member.
 17. The positioning jig device according toclaim 11, wherein said positioning robot comprises a multi-axis robotfor setting said vehicle frame to the desired attitude while the secondend of said positioning jig is operably connected to said positioningjig holder mechanism.